Rerun
by reminiscent-afterthought
Summary: [AU] A fated meeting takes place during the first Zero Reverse, and Dr. Fudo is sent back in time to stop the Momentum's creation and save his son's future. But who sent him back? Why? And when the Dark Signers and Yliaster stand in his way, how will he and his companions fight?
1. Arc 0 - Chapter 1

**A/N:** Finally, another 5D's MC, this one with a more regular update schedule planned, since it's a longer one. I'm hoping to update this bimonthly, alternating with a ZEXAL fic (otherwise I'd never touch some of my other fandoms :( ). If I don't stick to that, feel free to poke me until I do. I tend to respond to pokes.

The Arc 0 is the prologue arc; as a result, the arc and its chapters will be shorter than the others. The reason is that the two parts of the prologue don't go too well together in the same chapter, and the epilogue I currently have planned has the same problem. Splitting it like this seems to work better.

And that's about it from me. Enjoy, and let me know what you think.

* * *

**Rerun  
Arc 0: The Future Upon Them**

* * *

_An old pond;  
a frog leaps in  
the water sound_

_: An Old Pond :_

* * *

_**Chapter 1**_

By the time he had realised, the future was already upon them. Uncontrolled energy had surged through and decimated half the city in its blast. The cries of a thousand innocent souls suddenly ceasing resonated like an explosion within his ears. They drowned out the wailing of his little boy: the child that had been born just hours before, and he'd held just that once.

There wasn't time to think that he might never hold that little baby again. He closed his eyes a moment – the silence roared in his ears – and opened them again. The baby was gone – to safety, he hoped, or else he had become another of countless victims sucked up in the blast.

And the cause of it: his research, his lab, the generator – they were all gone. There was nothing but a vast expanse of black that had swallowed him whole, and for a moment he simply hung, suspended, in the air, in shock.

_Am…am I dead?_ he wondered. It wasn't an illogical assumption either; it was more feasible that he had crossed into the realm of death than his lab and its surrounding had been levelled to leave not even a trace of dust behind without touching him at all.

'Close enough,' a voice responded, much to his surprise. He could see no-one, hear nothing except his own breaths, now raspy as he strained his ears against the darkness, even as he struggled against whatever strange equivalent of gravity kept him in the air. 'You won't see me, Doctor Fudo.'

Many questions arose to his lips from that, but he kept them in check. A curious man he was, but not a foolish one. He sorted through his questions, asking first the most important one. 'Who are you?'

'I have been called many things,' the voice replied. Doctor Fudo noted its male tenor, as well as the metallic tint he had…almost as though he was automated: a machine, instead of a man.

'Indeed.' There was now a hint of amusement in the tone. 'You do your name credit, Doctor Fudo.'

The Doctor frowned at that. 'How is it you're able to read my thoughts?'

'It is not beyond my limits,' was the cryptic response. 'A great many things exist beyond the wall that appears before us.'

That raised more questions than answers, but the Doctor let it pass. 'What happened to the reactor?' was his next question.

There was a contemplative pause. 'What _will_ happen is the question you should ask, Doctor Fudo.'

'_Will_ happen?' The Doctor looked sightlessly about, despite the futility.

'In the future.' Another pause, but this time it wasn't contemplation, but…something else. 'I will show you.'

The darkness around him changed: shimmered, then lifted entirely to show two islands connected only by sea. They were like mirror images, reflections of one another: one crumbling with despair, the other bubbling with hope.

'Satellite and Neo Domino City,' the disembodied voice explained, and though the Doctor looked for speaker in the new light, he saw no other soul. 'This is the split that result from the Reverse Momentum. The split that threw half the city into the slums where they learnt despair, and the other half into the indulgence of the prospering new life they'd built, and greed.'

The Doctor frowned; he could hear bitterness in that voice, and mistrusted it.

'Oh, there was hope.' There was a hint of dark amusement with the bitterness. 'Hope in the form of a young boy from Satellite: Yusei Fudo.'

Doctor Fudo felt his breath catch in his throat at the mention of his son. 'He…he survives?' The relief is immediate: a cold wave that washes over him.

'For a time,' was the correction, which immediately caused the father's heart to plummet like stone.

'For a time?' The Doctor's throat went dry. 'How – why - ?'

'A chain reaction,' was the reply, and the scene began to move. A darkness rose out of the dilapidated island: the Satellite. It throttled the townspeople, those folk with their faces filled with despair. It throttled a dragon that briefly rose – a dragon he recognised: a key to the reactor. But it fell into the darkness too, as well as the duellist who owned it.

He saw the face, briefly. It looked just like his own._ Yusei…_

'And that is but one of many possible futures.' The voice, surprisingly, did sound sorry. 'And the kindest, perhaps.'

The scenes morphed: rewound themselves, and replayed to give different futures. Surviving the darkness that spread over Satellite, only to be killed by a friend. Surviving _that_, only to die at the hands of the one he, the father, had trusted hope and the future to.

'And even if that darkness is defeated…'

The scene changed entirely. Satellite and Neo Domino City were linked by bridges and prosperity had spread to both halves. But there was greed as well: higher violence rates, higher crime. And the terror that slowly descends, until Stardust Dragon and Yusei Fudo fall to it or fly into its heart to destroy it. Either way, no future beyond that shows his son.

And yet, Doctor Fudo finds himself unable to look away. The future had mellowed out a little: the image of false peace. Synchros flourished. The people revered the name of Yusei Fudo.

'A false peace indeed.' The voice sounded defeated now. 'Of course, it didn't last. Zero Reverse happened again.'

_Zero Reverse?_ the Doctor wondered. But he thought he knew what it meant.

'The name they gave to the Reverse Momentum.'

And this time he saw it: the blast of negative energy wiping a city off the map. He saw the people suddenly consumed and destroyed before a scream to tear from their lips: could hear the agony of thousands of souls as they suddenly ceased to exist, and the terror as the effects, this time, rippled outwards, to other reactors, other countries, until the entire world was in a similar state.

And he was staring at a ruined world in which only four people walked: the last of a desolate mankind.

Then it was darkness again, the darkness that resonated with the future's horror and despair.

Doctor Fudo was silent, thinking of what he had seen until spoken to again. 'This future can still be changed – if the root of the problem is gone.'

'The Momentum,' Doctor Fudo breathed, before the heaviness in the air stifled him again. 'It's too late; the Momentum has already – '

'The past can be changed,' the voice, still unnamed, replied. 'It _must_ be changed, before the Momentum can set the stage for these futures.'

The darkness began to lift again, but this time it gave way to nothing but dizziness. Light appeared, but it was dark, indistinct. The voice he'd been conversing it began to fade as well.

'_You_ will have to change it, by making sure the Momentum is permanently destroyed...'

And then Doctor Fudo found himself swallowed by a hazy white, with screams resonating in his ears anew as the past rewound into the present.


	2. Arc 0 - Chapter 2

_**A/N:**__ Oh wow, I actually made it…okay, one day late, but close enough. Probably the only fic that did. *shakes head* I think RL's more on line now, so hopefully the updates will behave themselves. Bimonthly was too crazy for me (ideas got cross-matched which doesn't work unless I'm trying to plan a new crossover), so we'll see how attempting monthly goes. _

_This time the focus is on Z-ONE, and I've never actually read or written about him, so this will be interesting. Enjoy. :D_

_Next chapter starts the beginning of the first arc!_

* * *

_**Rerun  
Arc 0: The Future Upon Them**_

* * *

_An old pond;  
a frog leaps in  
the water sound_

_: An Old Pond :_

* * *

_**Chapter 2**_

The Momentum had destroyed everything, including their hope. There was nothing left in his world; not even the sun came up anymore, and the temperature was slowly dropping. His heartbeat was, independently, slowing, and it was only a matter of time before one or the other killed him.

And when he died, the world would truly be dead, nothing save the graveyard of technology that no longer had mankind to control them. Water bled into the earth, wasting away because not even an ant still lived to swallow some. Trees had rotted into unfertile soil, destroyed by the miasma that continued to stifle their world.

They'd had to stop depending on food; it could not grow, and what existed was either eaten away by the scraps of life or destroyed by the machines that fulfilled their life duty of destruction. But even those were now gone; nothing moved outside; there _was_ nothing to move. Not even stars in the sky appeared, or clouds, or the sun. They were all gone.

It was technology that had let the few who'd survived the massacres live on, but technology was not infallible. They could travel through time but not turn it back. They could prolonged their lives but not make themselves immortal. They knew it would always be impossible: within their time, within their universe. So they made the choice to devote their lives and beings to preventing this catastrophe.

They tried many times. And each time ended in failure. Each time stripped away a little more of them, and of their hope. And now only he remained, clinging to the last thread of life and one last chance.

_To do what? What can I do?_

They'd been so sure that the legendary hero could save them, that he possessed the power to save them. A boy chosen by the Gods themselves; if he couldn't save them, what could?

But he couldn't. Each time loop ended in his eventual death, the world's eventual destruction. Sometimes they prevented the second Zero Reverse; something else came along and tore their peace down. Sometimes they didn't even manage that. On the rare instance his death occurred too early, at the hands of his city, his Government, or the Dark Signers.

Not once had they been able to reach a future where the world would continue to live and thrive, continue to be filled with humans, spirits, animals and plants: the symbiotic relationship the world was always meant to share. Not once had they managed to eradicate the source of their problems: the reactor. Not even the most extreme of measures had worked: the attempt to remove Duel Monsters from the face of history. And their attempt to remove the creator of the reactor had been met with even more disaster, for Yusei Fudo had also been removed from that timeline.

They didn't know why the fate of the world seemed to depend on the survival of one boy, but it did and most attempts to save their future failed because of it. And now there was only one more chance: one _last_ chance, to go back into the past and fix the future.

_Where? How?_

He didn't know, and he had little time to think about. Going to the timeline of Yusei Fudo after his powers had awakened as a Signer had been their first, and best, bet. But they'd tried that so many times. They'd even taken that Yusei to the first Zero Reverse, and the Yusei from the future to that time. None of those things had worked. They'd tried convincing Dr. Fudo to cease his research when it was young; most times he did, but someone else would pick it up and complete it. It was a fate they seemed unable to fight: the creation of the momentum that marked the destruction of not just mankind but the entire world they knew.

_What is it? What haven't we tried?_

There had to be something. Yusei: past, present and future had failed – but it wasn't Yusei who was failing. It was the strings of destiny being too many for one boy to face without snapping at least one of those strings. But that was just another thing that couldn't be changed. The momentum was destined to go off in his time. The Dark Signers were destined to awaken in his time. The Crimson Dragon was destined to come forth; the stone tablet was destined to fall from the sky – all in his time. The only thing it seemed not fated to happen in his lifetime was the destruction of their world; instead, his death was the catalyst they couldn't prevent.

In theory, all they could do was alleviate enough burdens from him for him to be able to handle the rest. But that seemed like an impossible task as well; Yusei's fate as a Signer was something that couldn't be changed; he was the only other person in the history of mankind to succeed in using Stardust Dragon's power, and he had failed to take that destiny upon him when he'd tried.

It occurred to him, then, that the person who'd created that card hadn't known its power would be tied to one man. Because that was wrong; the Signers existed in all generations; there had to be another one. But when the Signers only awoke once every five-thousand years, finding the sleeping one was like finding a needle in a haystack.

Z-ONE groaned; even if he had his cherished companions and the time he might fail to find that person. And even if they could, unleashing that power could possibly be beyond them…just as it had been impossible for him.

_There has to be a way. There just _has_ to be._

There had to be something in the past to answer that question; something in the infinite knowledge he'd amassed about that past. Yusei Fudo was central; that they'd confirmed long ago. Dr. Fudo was not, not to the creation of the reactor at least. And yet, Z-ONE recalled, that timeline had collapsed far more rapidly. In the first Zero Reverse. Completely annihilated.

_Can it be..?_

His oxygen saturation was dropping; ice was beginning to form on the tubes linked to his survival. Whichever was destined to steal his life first, he was running out of time. This was his last hope; Yusei Fudo could not save the world with a destiny of his weight on his back. Someone had to remove it; someone who could go forward and then back again in time to accelerate its flow, to bring certain events before their predestined time, to force that load to change.

It was risky, almost certainly doomed to fail. But he'd tried everything else, and he wanted to die with at least a glimmer of hope left.

_Dr. Fudo. It's up to you to save your son so he can save our future._


End file.
